Improvement in speaking-telegraphs



'I'. A. EDISON. Speaking-Telegraph.

No. 203,013. Patented April 30,1878* Nif UNITED STATES'- PATENT ()1.r1ncr3.1 v

THOMAS A. EDISON, OF MENLO rAnK, NEW JERSEY', ASSIGNOR To WESTERN UNION 'rnLEGnArH oOnrnNY, OF NEW YORK, N. Y.

' IMPROVEMENT IN sPEnKl-NGJELEGRAPHS.

Specifics-tion forniingpnrt of Letters Pntent N0. 20340.13, dll-led Afin so, 187s. Appncnnou inea Dpmber 1:3, 1877.

lTo all whom it may concern:

Be it known thatfl, THOMAs A. EDISON, of Menlo Iark, in the. county of Middlesex and State of New Jersey, have'invented an Improiement in Speaking-Telegraphs, of which the4 following is a specification.

The object of this' invention is to transmit and receive Oral communications over teleductor and the diaph mgm or other body moved by sound, to prevent false vibrations, and I employ an inducton-coil and a local circuit, arranged in such a manner Athat witha weaklocal battery, theline-'current is augmented yand the rise and fall of electric tension. is in proportion to the sonndvibrations. y

Figure lis a section of the `instrument fo transmitting; and Fig. 2 is a view at the rear ofthe diaphragm, showing the mannerof wind ing the rheostat-wiresi Fig. '3 showsthedia-` gram of connections for one' terminal station.

A is an induction-coil, consisting of one barof iron and two-coils', m' and m, the, latter being placed iu the main line in which the local hat ry c and the receiver also forms a part.

n is the primaryinductive-magnet, of very l w resistance, placed in a local circuit, 12, contninin g also therheostator reslsttmce-coils` h It 715l h4, Svc. t f I 3 e' ez c e, Svc., are springs, cach one being connected tothe juncture between each' resistancccoil. These springs e' e, 8vo., are contiguous to the spring D, and when thespring D isjmove'd it comes'invcontsct with e'- just a little before it does with e2, and so on.4 When e' and e2 are in contact' with D 'the resistance h' is out out of circuit, and it' e2 and e are in coxtact with 1) the resistance h.' is cut out, an so on, and contactbetween all the springs and D cuts all the resistance outpf cimuit.

m should he less than one ohm, und the, total' resistance of h'h, &c., about five ohms. Then the slightest movement of the spring D, wheny properly adjusted, will cause a great rise and fallin the strength of the magnetism in the core of'fm, und a consequent powerful induced l current will pass over the line and set the plate of the'receiverat'lhe distant station in 'vibration.

Ii' the diaphragm g isset in -powerful vibra- `tion n greater number of springs e'o, &c., come. in contact with D, and a greater/disturbance ofthe magnetism of the Vcore of m tukesplace, transmitting a'inore powerfulV wai-'edn .the

2 main line, which is in one direction whentlie diaphragm causes D to approach the springs, and in the contrary vdirection when, it lrecedes therefrom, thus the strength of the waves sent into the main line are proportionate tothe amplitude of vibration ofthediaphrsgm.

"I do not wish to conne myself to any-particular arrangement of the springs e c2 e3, 8vo., -Re they may be arranged to radiate from a ccnter, like-'a s'uniiower, .around a metallic. disk beveled inthe proper manner andsecured to the diaphragm, so as to,con1e in contac with one after the other of the springs as th diaf pliragm approaches. Itis not even necessary that the springs should be workedin a local circuit, as the `resistencia between each spring may he greatly increased' and the transmitter inserted directly in the main linewitl'i vthe re-' ceiver and battery.

Fig. 4 is a-modicntion of the rheostat; The same consists of a cylinder of insulating material having a thread cut in it from end to-end and containing woundjery tine platina wire, thetotal resistance of which maybe ve ohms. The forward movement of i the' diaphragm g causes the spring D to short-circuit each convolution of the wire, one after the other, yand thus decreases the resistance of the-local circuit.

AIn Fig. 5 the wireresistance is replaced by a semiconductor, such as plumbagoat G,in' ,eluded in the localfcircuit, the connections being'made by the metallic clamps K and H. t

For very powerful effects the resistanoeofv f is a piece of rubber .tubefastenedto the,

diaphragm and faced with a thin piece of platina-foil, g', which acts in the same manneras the spring D in Figs-2, 3, and 4. The for- 'the current to pass through the platina, ac-

cording lto the amplitude of the diaphragm-vibrations. 0f course other materials, such as silicon, boron, sulphides ot' the heavy metals, and other conducting chemical compounds, may be used, or even very thin strips of gold, platina, silver, and other metals may be used in the same manner as the plumbago.

In Fig. G the change in the resistance of the coil of wire takes place longitudinally, a spiral of insulated wires being arranged on a stud of insulating material, and compressed or allowed to expand by the movement of the diaphragm, thu's causing the various con voiutions to shortcircuit one another.

By 'this construction of apparatus and arrangement of circuits I am enabled to transmit :pon the line electric nndulaticns proportionate to the length of line, so as te produce the proper response at the distant receivingmagnet B and v diaphragm-armature B', because the rheostat will cause more or less resistance in the local circuit and the polarity of m* will alternate with the rise and fall of the electric tension in the-local circuit, and the battery c, also being in the main line, will act to neutralize or augment the main-line current according to the polarity of that current and in proportion to the resistance of the local and mainline circuits, thus obtaining a pow-1 erful current on 'the line from a weak local current. The elastic cushion f, interposing be- .tween the diaphragm,or other article vibrated by the atmospheric sound-waves, and theshort circut'ing conductors of the rheostat, prevents any musical vibrations ot' either D or g, and causes a gentle yielding movement and change of electric tension in proportion to the sound without risk of false vibrations.

I do not claim herein the disk of plumbago G shown in Fig. 5 as this is similar to that shown in my application No. 130; neither do 1 herein claim the sheet-iron diaphragm form is shown in someof my former applications, and the resistance to theelectric circuit is also ,variedhy the motion of the diaphragm in said application No. 130. Therefore the same is not claimed herein.

I claim as my inventionl. In a'speakingtelegraph, the combination, with a diaphragm, of a rheostat or resistancecoils and a conductor vibrated by the diaphragm and acting to short-circuit more or less of the rheostat in proportion tothe amplitude of the vibrations, substantially as set forth.

2. In combination with a diaphragm actuated by sound-vibrations and a metallic conductor, an elastic cushion, f, interposed be tween the diaphragm and said metallic conductor, to more the latter iu proportion to the movement ot' the diaphragm, substantially as set forth. 3. In peaking-telegraph, the combination with the diaphragm .and rheostat, of a loca circuit and au induction-coil, substantially as set forth. l

4. In aspeakingtelegraph,au induction-coil, a rheostat, and a battery in a local circuit, and

induction-coil aud also through the battery,

substantially as set forth.

D Signed by me this 8th day of December, A.

THOS. A. EDISON.

Witnesses Gao. T. PINOKNEY,

Cms. H. SMITH.

ing an armature to the electro-magnet-,as that.

a, inainlne circuit passing through a second 

